[RFC PATCH v2 02/21] fuse-bpf: Update fuse side uapi

[Daniel Rosenberg <drosen@google.com>]

Adds structures which will be used to inform fuse about what it is being
stacked on top of. Once filters are in place, error_in will inform the
post filter if the backing call returned an error.

Signed-off-by: Daniel Rosenberg <drosen@google.com>
Signed-off-by: Paul Lawrence <paullawrence@google.com>
---
 include/uapi/linux/fuse.h | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index 76ee8f9e024a..0e19076729d9 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -576,6 +576,21 @@ struct fuse_entry_out {
 	struct fuse_attr attr;
 };
 
+#define FUSE_BPF_MAX_ENTRIES	2
+
+enum fuse_bpf_type {
+	FUSE_ENTRY_BACKING		= 1,
+	FUSE_ENTRY_BPF			= 2,
+	FUSE_ENTRY_REMOVE_BACKING	= 3,
+	FUSE_ENTRY_REMOVE_BPF		= 4,
+};
+
+struct fuse_bpf_entry_out {
+	uint32_t	entry_type;
+	uint32_t	unused;
+	uint64_t	fd;
+};
+
 struct fuse_forget_in {
 	uint64_t	nlookup;
 };
@@ -874,7 +889,7 @@ struct fuse_in_header {
 	uint32_t	uid;
 	uint32_t	gid;
 	uint32_t	pid;
-	uint32_t	padding;
+	uint32_t	error_in;
 };
 
 struct fuse_out_header {
-- 
2.38.1.584.g0f3c55d4c2-goog